New York detectives now believe a single killer is responsible for the dismembered bodies of young women, a male transvestite and a toddler found dumped along a pristine stretch of Long Island's south shore from 1996 to 2010, officials and investigators told ABC News.

That killer is still at large, prompting concern that he may strike again and claim more lives before he is caught.

This past May, just as beaches were preparing to open for the summer season, officials on Long Island said they thought the killings could be the work of more than one killer. They have since changed their minds.

After eliminating numerous early theories on where the possible killer might reside, police also believe the killer is probably a Long Islander.

"Serial killers evolve. They change their MO's. They don't necessarily do the same thing all the time. What's common here is the dumping ground, and the people who are victims: sex workers," said Suffolk County Police Commissioner Richard Dormer, nearly a year to the day since the first gruesome discovery along the ocean parkway.

Police believe that all 10 of the victims are linked to the sex trade, with DNA indicating that the toddler was the likely daughter of one of the victims.

The four most recently murdered victims had advertised as escorts on classified website Craigslist, and all four of their bodies were reportedly wrapped in burlap.

In the spring, a massive search uncovered six more bodies, some of them dismembered more than a decade ago. One victim was a female toddler between 18 and 24 months old. DNA tests links the toddler to one of the adult victims.

Investigators thought they might have uncovered the work of separate killers, but now Dormer says that theory has changed.

"It is our theory is the serial killer is working alone. The girls that he contacted with met him alone," Dormer said.

The police commissioner says that the victims are all linked to the sex trade.

The Catalyst: Missing Escort Shannan Gilbert

It was the search for Craiglist escort Shannan Gilbert that yielded the grisly discoveries. Gilbert disappeared the previous May after meeting a client in nearby Oak Beach. Her body has not been found.

But Gilbert was never matched with any of the remains found. Now, Dormer says, police think her case is completely unrelated to the other 10 victims.

"Our theory is that this is a coincidence. She went missing in Oak Beach and this has nothing to do with the serial killer," said Dormer.

Gilbert had a driver take her to her client's house, while the other girls arrived alone. Gilbert was seen running away into the reeds. The other girls never got away.

If Gilbert was murdered and dumped, police say her body isn't here, which police say is also inconsistent with the rituals of this killer.

When asked what happened to Gilbert, Dormer had no answer. "That's a mystery," he said "We have 10 bodies now. Ten bodies and no Shannan Gilbert…it's a mystery."